1. Field of the Invention
The present invention relates generally to an actuator used in various electronic components and a method of manufacturing the same and to an information recording/reproducing device including an actuator.
2. Related Background Art
Devices with piezoelectric elements (piezoelectric microactuators) include micro pumps and a normally closed type micro valve as indicated in xe2x80x9cPrototype of Micropump for Integrated Chemical Analysis Systemxe2x80x9d by Shoji et al., IEICE (The Institute of Electronics, Information and Communication Engineers) Transactions (C, vol. J71-C, No.12(1988), pp.1705-1711). Application examples of longitudinal effect piezoelectric actuators include positioning of a diamond tip in a precision lathe, driving of a needle in a scanning tunneling microscope. It has been discussed to use piezoelectric elements in micromachines, microsensors, or the like through further reduction in size and improvement in performance. In various fields in which the use of such piezoelectric elements has been considered as being impossible, it is expected to enable minute and precise control by the use.
On the other hand, with respect to actuators for HDDs (hard disk drives), it tends to be difficult to position a magnetic head with respect to a track of a medium due to the reduction in track width with the increase in density.
In conventional magnetic disk units, a seek drive of a magnetic head has been carried out using a voice coil motor (VCM) or a rotary VCM.
Based on such a background, two-stage actuators like those recently used in optical disk related devices (such as CD, MO, DVD, or the like) tend to be used in HDDs to increase positioning accuracy.
Generally, systems of the two-stage actuators include an electrostatic system, a piezoelectric system, a magnetostrictive system, and the like.
An example of such two-stage actuators is disclosed in JP 9(1997)-265738 A, which is shown in FIG. 24. In JP 9(1997)-265738 A, it is described that as shown in the figure, a head supporting mechanism (a suspension 25) to which a head slider (not shown in the figure) is fixed vibrates with respect to a coarse actuator (not shown in the figure) in a magnetic disk unit. In JP 9(1997)-265738 A, attention is directed to the increase in track density in a magnetic disk unit. In FIG. 24, a pair of planar piezo elements 23 are incorporated to be positioned on both sides of the rotation center of a head mount block (a mount part 22) as a fixation part where the head supporting mechanism (the suspension 25) to which a head slider is attached is fixed to the coarse actuator. The pair of planar piezo elements are operated differentially to allow the head supporting mechanism (the suspension 25) to shake minutely. Thus, the head slider and a head element fixed to the tip of the head supporting mechanism can be displaced minutely. The planar piezo elements 23 cannot generate a large displacement. However, the suspension 25 is allowed to rotate minutely about a hinge and thus the displacement of the planar piezo elements 23 is increased at the position of the head element by eight times. In JP 9(1997)-265738 A, it is described that the positioning of the coarse actuator and the minute positioning of the head slider and the head element by the minute movement of the head supporting mechanism are operated interconnectedly, and thus the accuracy in positioning of the head element in a track width direction is improved, which enables the track density to increase. It can be assumed easily from FIG. 24 that the suspension 25, the mount part 22, and the planar piezo elements 23 are formed individually and then are assembled to complete the positioning mechanism.
As described above, the piezoelectric elements in the conventional technique had a problem in that generally, the displacement generated thereby and the size thereof are small and the displacement is constrained depending on the configuration, which cause the decrease in displacement and voltage (i.e. efficiency). In addition, fine processing and the use of an adhesive or the like have been difficult in manufacturing processes requiring fine processing of elements with a piezoelectric thin film or the like.
In order to solve the aforementioned conventional problems, the present invention is intended to provide an actuator and an information recording/reproducing device in which synthetic resin is used as a shape maintaining sheet material, so that the element efficiency and processing precision are improved, and to provide a method of manufacturing the actuator.
In order to achieve the above-mentioned object, an actuator of the present invention includes a shape maintaining sheet, a piezoelectric member provided integrally on the shape maintaining sheet, and a pair of electrodes formed to sandwich the piezoelectric member. The shape maintaining sheet is formed of synthetic resin.
An information recording/reproducing device with an actuator of the present invention includes a slider on which a head is mounted, a head supporting mechanism for supporting the head through the slider, and a tracking member for tracking by the head through the head supporting mechanism. The actuator includes a shape maintaining sheet, a piezoelectric member provided integrally on the shape maintaining sheet, and a pair of electrodes formed to sandwich the piezoelectric member. The shape maintaining sheet is formed of synthetic resin. The head supporting mechanism includes the actuator, and the actuator is driven to displace the head minutely.
A first method of manufacturing an actuator according to the present invention is a method of manufacturing an actuator including a shape maintaining sheet, a piezoelectric member provided integrally on the shape maintaining sheet, and a pair of electrodes formed to sandwich the piezoelectric member, with the shape maintaining sheet being formed of synthetic resin. The first method includes: forming a lower electrode by thin film processing on a substrate processed in a shape of the actuator; forming a piezoelectric thin film; forming an upper electrode; and forming a shape maintaining sheet made of synthetic resin.
A second method of manufacturing an actuator according to the present invention is a method of manufacturing an actuator including a shape maintaining sheet, a piezoelectric member provided integrally on the shape maintaining sheet, and a pair of electrodes formed to sandwich the piezoelectric member, with the shape maintaining sheet being formed of synthetic resin. The second method includes: forming a lower electrode by thin film processing on a substrate; forming a piezoelectric thin film; forming an upper electrode; then processing the substrate, the lower electrode, the piezoelectric thin film, and the upper electrode in a shape of the actuator; and forming a shape maintaining sheet made of synthetic resin.
A third method of manufacturing an actuator according to the present invention is a method of manufacturing an actuator including a shape maintaining sheet, a piezoelectric member provided integrally on the shape maintaining sheet, and a pair of electrodes formed to sandwich the piezoelectric member, with the shape maintaining sheet being formed of synthetic resin. The third method includes: forming a lower electrode, a piezoelectric thin film, and an upper electrode on a substrate; processing them in a shape of the actuator using a lithographic technique; and transferring the lower electrode, the piezoelectric thin film, and the upper electrode onto a pattern formed of synthetic resin.
According to the present invention, the piezoelectric element can be formed using no adhesive and furthermore, a minute element can be obtained and the element can be designed without constraint. In addition, a considerably larger displacement can be obtained as compared to that in a conventional piezoelectric element. Particularly, when the actuator of the present invention is used as one for a magnetic head or the like, it is possible to obtain an actuator and an information recording/reproducing device that can be controlled with high precision. When the resonance frequency is low and a high speed control is difficult, size reduction is required. Even when the size is reduced, the displacement and voltage (i.e. efficiency) can be drawn out efficiently. Furthermore, the reduction in film thickness also enables power consumption to be reduced.